This invention relates to portable torches, burners, stoves, lanterns and heaters which use fuel from aerosol type containers, and in particular to a novel attachment therefore which provides an improved seal and structural strength.
In the past, it has been well known to provide portable propane torches and burners with refillable containers or "bottles". However, this has the disadvantage that due to the high pressure in the range of about 240-300 psi., the containers are considerably more expensive than the propane they contain.
More recently, attempts have been made to overcome this problem by using butane at lower pressures in disposable aerosol type containers which can be made much more economically. However, this has been found to have the problem that butane does not vaporize very well at lower temperatures, and thus difficulties have been encountered in lighting it when it is cool. The applicant has found that this further problem can be overcome by utilizing a suitable mixture of propane and butane at a pressure of approximately 75 psi. At this reduced pressure, a type Q aerosol container with a pressure relief valve in the bottom may be used safely, but it is desirable that the torch, burner, lamp, etc., be securely attached to the container. There are, of course, two potential problems with this type of detachable connections. The first is leakage of the fuel around the connection, and the second is the possibility of damage to the container as a result of the attachment to the container. This second problem is of particular concern as most conventional connections are made to the inner stem of the container, with the result that a considerable torque can be easily inadvertently applied to the stem through the attachment.
One example of an attempt to overcome these problems is shown in U.S. Pat. No. 3,732,060 to Churchill et al. which issued May 8, 1973 which shows each container attachment with a cap which fits inside a head and a single O-ring seal. An improvement is shown in U.S. Pat. No. 4,082,993 to Oakes which issued Apr. 4, 1978 wherein the attachment is secured to the stem of the container, but a locking ring is provided to transfer some of the stress to the rim of the can. However, this arrangement still has the disadvantages that only a single seal is provided and the user must remember to tighten the locking ring as well as make the initial connection.